   [pop argmap]
   (-> pop
       (nonempties-when-autoconstructing argmap)
+      (age-mediate argmap)
       (screen argmap)
-      (age-mediate argmap)
       (lrand-nth)))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

  [pop {:keys [epsilon-lexicase-epsilon] :as argmap}]
  (loop [survivors (-> pop
                       (nonempties-when-autoconstructing argmap)
                       (screen argmap)
                       (age-mediate argmap)
                       (retain-one-individual-per-error-vector))
         cases (lshuffle (range (count (:errors (first pop)))))]
    (if (or (empty? cases)

  [pop argmap]
  (loop [survivors (-> pop
                       (nonempties-when-autoconstructing argmap)
                       (age-mediate argmap)
                       (screen argmap)
                       (retain-one-individual-per-error-vector))
         cases (lshuffle (range (count (:errors (first pop)))))]
    (if (or (empty? cases)
